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Author Topic: Alpa STC Review  (Read 4729 times)
Anders_HK
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« on: April 24, 2011, 10:14:55 PM »
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Hi Michael,

Much kind thanks for your review. The STC is a very interesting camera, and one I am very keen on myself. One reason is its preciseness and another is that I believe it to be the first camera for digital back which can be used to quickly slide the back for panoramic capture (left, right). As such it appears as rather revolutionary for digital capture of panoramic landscapes for ultimate image quality using flat stitching.

Some comments to your article;

1. "... view cameras that we used for advertising, product and landscape shooting in the days of film"
- Film is an older media, but I would add that it is simply that and another media. While many of us find that we are using it less and less and even giving it up, film remains an alternative and a very good media for photographic capture. As such it is reasonable to assume it will be used as a specialty product in arts and by enthusiasts in long future still, although its market is shrinking.

2. "The way a DSLR is adjusted is a correction factor is found for a particular lens / body combination and this number is entered on the camera. ... Obviously only cameras with the ability to input an AF correction factor can be aligned, and currently this means only top-of-the-line pro-grade DSLRs from Canon, Nikon, and Sony."
- The Hy6 by DHW also have this ability and is per what I know the only MF camera to enable this.

3. Lenses adjusted by Manufacturer
- If I have the info right also Rollei Hy6/6008 lenses, and at least their AFD lenses are adjusted by Schneider. I am not certain if this is to the exact methods applied to Alpa lenses.

4. Alpa focus
- Another means to focus an Alpa is by zone focusing within the DOF that provides a sharp image (similar to a Leica). Thus works best for wides at an optimum (or acceptable) aperture that provides for a large DOF. I was told this works for max around 70mm, but I imagine it depends on also subject and subject distance.

Appreciate comments.

Regards
Anders
« Last Edit: April 24, 2011, 10:33:08 PM by Anders_HK » Logged
ErikKaffehr
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« Reply #1 on: April 24, 2011, 10:39:30 PM »
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Hi,

Not really replying to Anders comments but a question of my own.

As far as I understand the shimming on the Alpa is intended to get sensor position and focusing scale to match? What about axial alignment of sensor and lens? I presume that there are tolerances in this regard on both camera and lens?

Best regards
Erik

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Graham Welland
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« Reply #2 on: April 25, 2011, 01:06:55 AM »
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Shimming on the Alpa is indeed to get the sensor plane in the right place with respect to your lens at infinity. If you need to adjust for off axis correction then you can achieve this by cutting down a shim and placing it in the appropriate place, although this is atypical.

One slight consideration with the shimming is that you normally do this with your longest lens since this makes it easier to view distant objects. However, the resulting adjustment between the back and the lens is really only correct for that lens on the body. The assumption is that all lenses are adjusted to perfection and I can state from personal experience with my Alpa Schneider & Rodenstock lenses that sometimes this is NOT the case. For example, I just had to have my 47 XL APO-Digitar corrected as it was significantly back focusing at infinity compared to my 90 Rodenstock HR-W & 150 Schneider. Now the adjustment for the infinity setting on the wide angle lens is very very slight and my dealer corrected this using their collimeter.

In all fairness it's probably also worth pointing out that precise setting of back to lens adjustment / correction can also be achieved with Arca's solution. That does have the ability to configure unique offsets for the back/lens combination on the body which in reality the Alpa shimming solution can only achieve for one lens/back adapter/back (with the assumption that this is the same for all other lenses you have of course).

Btw, I'm a huge fan of my STC. I traded my Max and gave up the dual axis adjustments for this camera but for travel & landscape work it's a superb lightweight solution. Compared to the space required for the Max, the STC is tiny and much more convenient. When you start adding longer lenses and the short barrel adapter to the STC (or TC for that matter), the camera pretty rapidly gains weight and bulk. With my 150 & SB adapter & P40+ on the STC you are looking at a camera that is as big and almost as bulky as the 645DF with 150D on it. However, with the 47mm it's very compact.

One last thing, I notice that almost without exception the Alpa and other tech cameras are pictured without the sync cabes for the digital back. The reality is that when you're shooting in the field there's always at least a sync cable from the lens to the back and unless you're using the finger shutter release there's also a cable release. For Phase One backs you may also have even more cables if you're using a wake up release.

Just trying to keep everyone honest here ...  Grin
« Last Edit: April 25, 2011, 01:16:58 AM by Graham Welland » Logged

Graham
dchew
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« Reply #3 on: April 25, 2011, 06:21:42 AM »
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Having just made the switch myself from a DSLR to MF/Alpa, I couldn't be happier.  Love the way it works in the field.  I was on a tripod focusing with live view when using the Canon, so although the Alpa certainly is slower, it's not that much different in my experience.

I like the HPF rings not only for their precision but also because they allow a second adjustment:  individual lens to back.  I have two lenses, the 43xl and the 100HR-S.  I calibrate to the 100, but the 43 is a bit off when I test that too.  By shimming to the 100 (which requires the least amount of shims), I can simply reposition the HPF ring on the 43 so that infinity is not at max focus rotation.  Now both lenses are accurate.  I guess I need a third lens to tell which of the first two needs to go back for adjustment. :-)

One point about the article:  I think 43mm and 120mm correlates to 28mm and 77mm on a P65/IQ180; not 35mm and 90mm as stated in the article.  A 150mm along with the 43 would be my two-lens kit.

In regards to viewfinders, I seem to be getting along pretty well with none.  But if I break down and get one it will definitely be the iPhone holder.  Looks like the iPod Touch and the holder would be half the price of the normal viewfinder, and more accurate and versatile.

Dave
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tsjanik
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« Reply #4 on: April 25, 2011, 06:51:40 AM »
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.................2. "The way a DSLR is adjusted is a correction factor is found for a particular lens / body combination and this number is entered on the camera. ... Obviously only cameras with the ability to input an AF correction factor can be aligned, and currently this means only top-of-the-line pro-grade DSLRs from Canon, Nikon, and Sony."
- The Hy6 by DHW also have this ability and is per what I know the only MF camera to enable this..................



The Pentax 645D allows correction factors as well (as does the K5 for that matter).

Cheers,

Tom
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buckshot
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« Reply #5 on: April 25, 2011, 07:32:09 AM »
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While Michael states that 'Alpa is the only MF technical camera to offer a shimming solution for MF backs' it is possible to shim the Cambo Wide RS - I have written about how to do it here. This isn't a solution from Cambo - rather a home grown one - but it works. Also, I believe that the latest sliding back from KG for the RM3D has this ability also: 'A new feature permits the discriminating photographer to fine tune the plane of focus (if needed) precisely to a specific digital back assuring accurate lens focus at infinity.'
« Last Edit: April 25, 2011, 07:34:37 AM by buckshot » Logged
AFairley
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« Reply #6 on: April 26, 2011, 11:14:26 AM »
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""The way a DSLR is adjusted is a correction factor is found for a particular lens / body combination and this number is entered on the camera. ... Obviously only cameras with the ability to input an AF correction factor can be aligned, and currently this means only top-of-the-line pro-grade DSLRs from Canon, Nikon, and Sony."

Just to speak up for orphan child Olympus, the E-30 and E-5 have this feature.
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Ben Rubinstein
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« Reply #7 on: April 26, 2011, 12:07:22 PM »
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What I don't get is shimming a back to within a 0.001 of a mm but then using a laser rangefinder for focusing which cannot begin to be aimed accurately to within even a 0.5 of a mm of the sensor plane reliably nevermind 0.001 of a mm...

Or am I missing something?
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michael
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« Reply #8 on: April 26, 2011, 01:02:06 PM »
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Ben,

Yes, you're missing the point that the sensor and the film plane need to (or at least can be) made accurate to within .01mm, but that doesn't mean that the lens needs to be focused with that level of accuracy. These are completely different requirements.

The laser is accurate to within about 1/4" at any reasonable distance, and this is well within the DOF of just about any lens. It's also easily settable with great accuracy using the HPF focusing rings.

Michael




« Last Edit: April 26, 2011, 04:35:56 PM by michael » Logged
JohnTodd
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« Reply #9 on: April 26, 2011, 03:19:07 PM »
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Ben,

Isn't one a fraction of the distance from the sensor plane to the (nodal center?) of the lens, whereas the other is a fraction of the distance from the (nodal center?) of the lens to the subject, which are usually vastly different?
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tho_mas
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« Reply #10 on: April 26, 2011, 04:34:38 PM »
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- as said above the Cambo WRS can be shimmed easily. Either DYI. Or you could also let Cambo adjust the rear standard (the rear standard of the WRS is adjustable at 4 points so you can adjust the overall sensor distance or you can as well adjust off axis misalignement of the sensor if required)
- the Rm3D doesn't need shimming by design (you just have to offset the distance indication on the lens; as the scale is linear you can use the same offset for all your lenses at all distances)
- AFAIK Sinar also adjusts the camera interface with shims
- you can adjust every digital large format lens to match the infinity indication very easily by adjusting the focus ring of the lens; doesn't take much longer than 10 minutes for each lens

So the Alpa shimming set is a great and very effective offer. But it's clearly not the only system that allows an adjustment of the sensor spacing.

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Ben Rubinstein
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« Reply #11 on: April 26, 2011, 05:08:52 PM »
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I've learnt something new today, I'd always been puzzled by the use of laser rangerfinders or the sonic focus thingy but now I understand, thanks!
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John Camp
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« Reply #12 on: April 26, 2011, 07:54:16 PM »
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I have some sincere questions about Alpa and other high precision MF backs.

1. How big do you have to print to take advantage of a well-tuned Alpa body/lens/back combination, to distinguish it from an ordinary well-tuned MF camera/back combo?

2. How well do you have to print to take advantage of the precision offered by the Alpa, compared with other well-tuned MF camera/backs?

3. The Alpa has a grip. Does this imply some function as a hand-held camera, or is it purely a tripod-mounted device?

Thanks

JC

 
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dchew
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« Reply #13 on: April 26, 2011, 08:39:46 PM »
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John,
I don't think your first two questions can be answered without perceptions/preferences/opinions.  But I will say it is pretty big.  I think it is important to point out most of the reason for shimming is to help with focusing.  If backs had live-view like a DSLR, there wouldn't be much point except to make sure it focused at infinity.  Live view would provide direct focus feedback and would eliminate several links in the chain and auto correct for any positioning error that shimming corrects for.  Shimming ensures the distance scale on the lens is correct.  It has nothing to do with how you set the lens scale and how you measure the distance.

In my interpretation with prints, I can see the difference between 0.01-0.02mm shims once the print gets to 20" on the long edge.  Of course that depends on a lot of other factors (primarily the type of image).  But if I had a good live-view, I would definitely use that to fine tune focusing regardless of what the focus scale says.

In regards to the third question, yes.  There seem to be several people who use the Alpa hand-held.  Several threads and images on the getDPI forum.  It is actually quite good for that; small*, quiet, and surprisingly fun.  I don't shoot that way much and have not had the Alpa for very long, but when I have shot hand-held the results were better than I expected.  Not as good as a DSLR on a tripod, but not bad.  Alpa seems to promote it as a very capable camera for hand-held shooting.  However, I have a 100mm lens and it is often hard for me to find the shutter release!

Dave

*small for a MF camera!

I have some sincere questions about Alpa and other high precision MF backs.

1. How big do you have to print to take advantage of a well-tuned Alpa body/lens/back combination, to distinguish it from an ordinary well-tuned MF camera/back combo?

2. How well do you have to print to take advantage of the precision offered by the Alpa, compared with other well-tuned MF camera/backs?

3. The Alpa has a grip. Does this imply some function as a hand-held camera, or is it purely a tripod-mounted device?

Thanks

JC

 
« Last Edit: April 26, 2011, 08:44:33 PM by dchew » Logged

MatthewCromer
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« Reply #14 on: April 29, 2011, 04:25:28 PM »
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It seems to me that all the fuss about "shimming" is irrelevant if you are using a back with liveview and a magnified zoom.  Correct?
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Anders_HK
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« Reply #15 on: April 29, 2011, 04:43:51 PM »
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I gather yes and no:

1. Yes if you are at all times using live view to focus. Hand held?

2. And if sensor in back is within 0.01mm tolerance PARALELL to Alpa system/lens.

Regards
Anders
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MatthewCromer
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« Reply #16 on: April 29, 2011, 07:49:47 PM »
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Well I never shot my view camera handheld.   :-)
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vjbelle
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« Reply #17 on: May 01, 2011, 02:00:59 PM »
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2. And if sensor in back is within 0.01mm tolerance PARALELL to Alpa system/lens.


This is where REAL tolerance is necessary.  The whole system falls apart if it isn't perfectly parallel.  Been there.....done that on an Alpa with various lenses.  I have seen parallel tolerance issues with a 72mm Digitar and 120mm Digitar.  In fact, my H2 and Phase P45 were tighter in that area.  I would fault the lenses in all circumstances..... a real shame for all the money that Alpa is asking for those lenses.  They really should be perfect!

Victor
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